In Lost's 100th episode, Daniel's return to the island threatens to bring the castaways' lies to the Dharma Initiative into the open, causing a split in their ranks with violent repercussions for some of the gang.

More will be revealed about Daniel's past, including how he came to learn that Desmond would be his 'constant' and quite how 'the variable' will affect the mysterious hatch where the Losties first found Desmond.

There will also be revelations about Daniel's mother, Eloise Hawking, and her relationship to Charles Widmore will come under the spotlight.